Immunocytochemical localization of vinculin in muscle and nerve

A complete survey of the immunofluorescence distribution of the cytoskeletal protein vinculin in the normal skeletal muscle and peripheral nerve of humans and of different rodent species was performed. Our results enable us to localize vinculin in different types of adhesion plaques such as sarcolemmal costameres and neuromuscular and myotendinous junctions, but also in a fine intermyofibrillar lattice, possibly associated with intermediate filaments and/or with the triads. Moreover, we describe the presence of vinculin in junctional domains of several, previously unrecognized, specialized cells such as: the outer sheath of the muscle spindle capsule, the multilayered flat cells of the perineurium, the smooth muscle cells of epineurial blood vessels, and the endothelial cells in the endoneurium. These data call for a major role of vinculin in mechanisms of adhesion between cells, between cell and substrate and between intermyofibrillar components in the neuromuscular system. Such knowledge provides an anatomical background for studies on the possible pathological effects induced by an impairment in vinculin function.